Even before he arrived at the summit in the picturesque town of La Malbaie, Que., on Friday, Mr. Trump had skirmished over Twitter with Mr. Trudeau and French President Emmanuel Macron over stiff USA tariffs on steel and aluminum from Canada, Europe and Mexico.
At the start of the Trump's presidency, many foreign leaders worked to develop cordial relationships with him, hoping that it would help to make Trump more willing to compromise on some of his more contentious campaign promises.
And France's President Emmanuel Macron, who met Trudeau in Ottawa before they headed on to the summit, said he would rally support from his British, German and Italian counterparts before they all sit down with Trump. In the exchange Trump reportedly said, "Didn't you guys burn down the White House?".
"Canada will not change its mind when it comes to illegal and absolutely unjustified application of tariffs", she said on Friday.
Macron and Trudeau both were expected to have formal meetings with Trump later in the day.
Canada, Mexico and the European Union have separately announced retaliatory tariffs.
For the past week, it was an open question in official Ottawa whether Trump would actually show up, given his recent trade actions against the other G7 countries and his increasingly antagonistic comments about their approach to worldwide relations.
"There's a lot of questions hanging over it but think about this: at least we have CETA", said Jason Langrish, executive director of the Canada Europe Roundtable for Business.
Nevertheless, Trump told reporters Friday that he has been "Russia's worst nightmare".
It's also no secret that the United States and Canada haven't exactly been getting along as of late - particularly on the issue of trade and tariffs.
"I agree with President (Trump)". After its annexation of Crimea, the other seven members shrunk the bloc and effectively kicked Russian Federation out until further notice, starting with a summit in 2014. Moreover, later it became known that Trump not only talked about the possibility of a meeting but also invited Putin to Washington for this.
Trump's suggestion of readmitting Russian Federation was unlikely to gain any traction at the gathering of the group that includes the United States, Canada, Japan, Britain, Italy, France and Germany. Last June, even before Trump announced possible new tariffs targeting our major trading partners, Pew Research Center found big shifts in how people around the world viewed the United States.
The best-case scenario for Friday was apparently that Trump, who over the past 24 hours had on multiple occasions expressed vitriolic opposition to his allies' trade policies on Twitter, would not blow the same kind of steam as he faced their criticisms in person during meetings about the economy.
Over the course of his presidency, Trump has inflamed allies with his isolationist policies, including withdrawing the USA from the Paris climate accord and the global Iran-nuclear agreement.
Trump also said at the time that he was undecided about the climate change agreement.